Making a Museum: Science of Materials 


By JuWayne Tanner

Material Science is a blend between the worlds of chemistry and engineering. In our modern world, technology advances so fast that some things seem to operate on pure magic. Understanding the nature of different materials gives us insight into the science of how things really work.

Tensile Strength:

Have you ever crossed a rope bridge and hoped that the rope wouldn’t break before you got across? The performance of that bridge depends on the tensile strength of the rope. Rope, hair, fishing line, wire cable, sewing thread; all of these have different tensile strengths. Tensile strength is a measure of how hard you can pull the ends of a material apart before it will break.

One of the most effective ways to test the tensile strength of a material is to apply a load (such as hanging weights from it) until ultimate failure (when the material breaks into two pieces). Although testing materials for failure ourselves makes for great destructive fun; tens of thousands of materials have been previously tested to save us some time. With those data, we can formulate our own calculations. In the engineering community, cost and performance considerations are usually our top priorities.

Good engineers try to choose materials that will be strong enough to do the job safely. There are thousands of choices of ropelike materials to choose from, but we need to consider numerous factors like corrosion and abrasion resistance, weight, cost, and tensile strength to find the right one for each job. 

Malleability of Metals:

Why do some metals bend easier than others? Aluminum cans are easy to crush, while soup cans are much stronger. What makes some materials super hard and others soft and pliable?

These metals owe these characteristics to a property called malleability: the ability of metallic substances to form, flatten, or bend. A metal’s malleability depends on its atomic structure. Each atom has valence electrons that it can share with neighboring atoms to create a bond. This type of metallic bond allows the atoms to slip and bend past each other while still being bound together by the shared electrons. Metals can be more or less malleable depending on the quantity of electrons available to create bonds between atoms.

Ferrofluids:

Have you ever seen a black oily liquid that can be moved with a magnet?

Ferrofluids are an exciting old-yet-new technology that is creating new possibilities in the world of engineering. They consist of tiny magnetic particles suspended in a liquid. When a magnetic field is applied to the liquid, the particles respond in exiting ways. Electromagnets make ferrofluids even more interesting. The ability to magnetize a surface with the flip of a switch is an absolutely awesome capability with limitless applications. By energizing a neighboring electromagnet, you can instantaneously turn a liquid ferrofluid into a solid!

To experience some of these amazing materials firsthand, come visit the STEM Saturday event on December 10th at the McCroskey House at Tumbleweed Park in Chandler! Bring the whole family any time between 10am and 1pm for some exciting engineering fun!

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